The three key characteristics of spring-loaded contacts are the height, working range, and operating force. The height of the spring-loaded contact refers to its length when it is uncompressed and at rest. Working range is a critical characteristic of spring-loaded contacts, as it determines the amount of variation in the height and position of the mating surfaces that the spring-loaded contact can accommodate, ensuring that the electrical connection is made even when the surfaces are not perfectly aligned. The working range of a spring-loaded contact is typically smaller than the full range of motion between the uncompressed height of the contact and its fully compressed height. Small buffer areas are required at the beginning and end of the full range to ensure stable contact resistance. In these buffer areas, the electrical contact between the spring-loaded contact and its mating connector may be less stable, and the contact resistance may fluctuate, leading to potential reliability issues. This is why it is important for engineers and designers to carefully consider the working range of the spring-loaded contact and its impact on the overall performance and reliability of the connection.